[zanny]

I started using bitfinex recently. Other exchanges I've used have had miriads of downtime, and I just moved off campbx because their site is so slow (and their market cap has shrunk huge). The other plus is that their fees are often half of other exchanges, I went from a .5% comission on cbx for sales to a .15%.

Bitstamp is also good, I hear, but I just went with finex because their fees are lower =P.

I think it is important to use an exchange outside the US though, because I expect the fed to start going Orwell on any bitcoin company soon.